Drilling hammer having an external mechanism for selectively switching operation between impact drilling and chiseling modes

ABSTRACT

The present invention relates to a drilling hammer comprising a hammer tube ( 13 ) that is rotationally drivable inside a housing ( 10 ), a striking tool ( 14 ) located in the hammer tube ( 13 ) and provided with a piston ( 15 ) that can driven with a reciprocating motion, and an operating mode change-over switch ( 35 ) for the “impact drilling” and “chiseling” operating modes. The hammer tube ( 13 ) is decoupled from its rotary drive when in the “impact drilling” operating mode and is secured in the housing ( 10 ) in a non-rotative manner when in the “chiseling” operating mode. To obtain a switching mechanism ( 37 ) of the operating mode change-over switch ( 35 ) having a very flat design and requiring little installation space, an actuator ring ( 48 ) is fixed on the hammer tube ( 13 ) in an axially displaceable and torsion-proof manner, the actuator ring including at least one radially projecting locking spline ( 51 ) on its outer side facing away from the hammer tube ( 13 ), the locking spline being capable of engaging in at least one axial recess ( 52 ) in the gearbox and in locking toothing ( 53 ) in the housing. Rotational motion of a control button ( 36 ) of the operating mode change-over switch ( 35 ) is converted to axial displacement of the actuator ring ( 48 ) on the hammer tube ( 13 ) by the switching mechanism ( 37 ). In addition, the operating mode change-over switch ( 35 ) can be used to activate a “drilling” operating mode, in which the striking tool ( 14 ) is decoupled on the drive side.

CROSS-REFERENCE

The invention described and claimed hereinbelow is also described inPCT/DE 03/02512, filed on Jul. 25, 2003 and DE 102 61 030.4, filed Dec.24, 2002. This German Patent Application, whose subject matter isincorporated here by reference, provides the basis for a claim ofpriority of invention under 35 U.S.C. 119(a)–(d).

BACKGROUND OF THE INVENTION

The present Invention is directed to a drilling hammer.

It is commonplace today to equip drilling hammers having a certainrating such that they can be used in the “impact or hammer drilling”operating mode, in which the striking tool hammers the work piece in theaxial direction while the tool is simultaneously started rotating usingthe tool holder, and they can be used in the “chiseling” operating mode,in which only the striking tool is activated and the rotational drivefor the tool holder is turned off. Since a single electric motor drives,via a gear unit, a hammer tube that is connected with the tool holder ina torsion-proof manner, and it drives the striking tool via a crankdriving mechanism, the piston of which makes a reciprocating strokingmotion in the hammer tube and acts on a beater which, in turn, transfersthe impacts to the end of the tool via a snap die, an operating modechange-over switch is provided that separates the hammer tube from thegear unit in the “chiseling” operating mode and secures it againstrotation in the housing. In this mode, the rotatably supported drivengear of the gear unit encompassing the hammer tube is separated from thehammer tube.

SUMMARY OF THE INVENTION

The drilling hammer according to the present invention has the advantagethat the switching mechanism of the operating mode change-over switch isvery flat in design and the axial extension of the operating modechange-over switch can be kept small due in particular to a narrowactuator ring. The flat design allows the housing cover on which themanually operated control button is mounted to have a low profile andthe width across corners of the drilling hammer, i.e., the distancebetween the center of the switching mechanism and the upper edge of thehousing, to be kept small. A single locking spline is sufficient toestablish a torsion-proof connection between the actuator ring fixed onthe hammer tube in a torsion-proof and axially displaceable manner andthe driven wheel of the gear unit. Preferably, a large number of lockingsplines distributed around the circumference of the actuator ring isprovided, the locking splines being axially insertable into acorrespondingly large number of axial recesses in the driven wheel. As aresult of the large number of locking splines and axial recesses, theactuator ring—which is made of metal—can transfer higher torque, and mayalso be made of plastic. In addition, given the non-aligning orientationof locking splines and axial recesses, a very small path of rotation ofthe hammer tube is required to snap the actuator ring into the drivewheel. If the guide splines on the actuator ring provided for atorsion-proof connection and guide grooves in the hammer tube areequidistant, the actuator ring can be slid onto the hammer tube in anyrelative position, which makes installation easier. The switchingmechanism can be designed to be very compact and stable despite thesmall overall size, thereby ensuring a long service interval.

According to an advantageous embodiment of the present invention, theactuator ring is located on the side of the driven wheel facing awayfrom the control button and is connected in a fixed manner—underneaththe drive wheel and past it—with a coupling ring slid onto the hammertube on the other side of the driven wheel, the coupling ring beingcoupled to the control button such that switching the control buttonbrings about an axial displacement of the actuator ring. Due to thisstructural design, the switching mechanism on the hammer tube is locatedunder the driven wheel of the gear unit so that the width across cornersof the drilling hammer is determined only by the outer diameter of thedriven wheel—which is typically designed as a ring gear—and is minimizedby it.

According to an advantageous embodiment of the present invention, theconnection with the coupling ring, which is preferably made of plastic,is realized using two cantilevers, which extend integrally with thecoupling ring axially away from said coupling ring and accommodate theactuator ring in recesses located near its ends. The actuator ring canbe installed easily by pressing the two elastically outwardly preloadedcantilevers together. The circumferential play of the cantilevers iskept greater than that of the actuator ring on the hammer tube, so thatthe cantilevers need not transfer any torque.

According to an advantageous embodiment of the present invention, thecoupling ring is coupled to the control button via a shift fork that isguided with a projection in an annular groove in the coupling ring,whereby the coupling takes place via a synchronizing spring retained onthe shift fork and an eccentric pin located on the control button, onwhich said eccentric pin the legs of the shifter fork bear in anon-positive manner at diametral points. The large synchronizing springallows the operating mode change-over switch to be changed over easilyand reliably. The shift fork and the coupling ring can be fabricatedeconomically out of plastic. The size of the control button makesoperation easier and also permits handling using work gloves.

According to an advantageous embodiment of the present invention, afurther setting position for the “drilling” operating mode is assignedto the control button; in this mode, the striking tool is decoupled fromits drive when the hammer tube rotates. This decoupling is not broughtabout by the axial displacement of the actuator ring on the hammer tube,but rather by the displacement—at a right angle thereto—of a switchingmechanism part that separates a coupling located in the drive chain ofthe striking tool. To this end, a switching ramp which extends across anangle of rotation is configured on the control button, preferably on itsunderside, the switching ramp rising in the direction of the axis ofrotation of the control button. The switching mechanism part ispreferably configured as an axially displaceable separating slide, whichbears against the switching ramp in a non-positive manner and against adisplaceable coupling part of the coupling that, when displaced axiallyagainst the force of a coupling spring, the coupling can be released.The low spring force of the coupling spring and a spring provided on theseparating slide for bearing against the switching ramp in anon-positive manner permits the operating mode change-over switch to beoperated in an easy yet reliable manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is explained in greater detail in the descriptionbelow with reference to an exemplary embodiment presented in thedrawing.

FIG. 1 shows, in sections, a longitudinal sectional view of a drillinghammer with an operating mode change-over switch,

FIG. 2 shows a perspective drawing of a switching element of theoperating mode change-over switch in FIG. 1,

FIG. 3 shows the switching element according to FIG. 2, in a perspectivedrawing, the switching element having been partially extracted from ahammer tube of the drilling hammer,

FIG. 4 shows a top view of a control button of the operating modechange-over switch in FIG. 1,

FIG. 5 through 8 show a top view of a control button lower part and acoupled shift fork of the operating mode change-over switch in FIG. 1 infour different setting positions of the control button,

FIG. 9 shows a profile of the control button lower part with switchingramp for actuating a vertical separating slide of the operating modechange-over switch in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drilling hammer shown in a sectional view in FIG. 1 with its rearregion in a longitudinal sectional view includes a housing 10 with ahousing opening 11 that is closed by a housing cover 12. A tool holderextends out of housing 10 at its left end, which is not shown in FIG. 1,on which a tool is mounted in a limited axially displaceable manner. Thetool holder is connected in a torsion-proof manner with a hammer tube 13rotatably supported in housing 10. An air cushion striking tool 14 witha piston 15 capable of being displaced axially in hammer tube 13 islocated in hammer tube; the air cushion striking tool can be broughtinto reciprocating motion using a crank driving mechanism 16 located ina drive chain between an electric motor 27 and piston 15. Air cushionstriking tool 14 further includes a beater driven by piston 15, thebeater acting via a snap die on the end of the tool mounted in the toolholder. To this extent, the drilling hammer described here conforms withthe drilling hammer described in DE 38 26 213 A1, whereby thearrangement and configuration of the tool holder, hammer tube 13 and aircushion striking tool 14 with piston 15 described there also apply tothe drilling hammer described here.

Crank driving mechanism 16 includes a crank wheel 18 with an integralbearing tube 181 and a crank pin 19 positioned eccentrically to the axisof rotation, on which a push rod 20 bears in a rotatable manner, thepush rod being connected with piston 15 of air cushion striking tool 14in a swivelling manner. Crank wheel 18 is supported In a rotationalmanner with its bearing tube 181 on an axis 17 in the housing. A gearwheel 21 with external teeth 22 is situated on bearing tube 181 In arotatable and axially displaceable manner. A coupling spring 23configured as a coil compression spring bears between crank wheel 18 andgear wheel 21, the coupling spring pressing gear wheel 21 on the frontside against a separating slide 24 described in detail hereinbelow. Inthis displacement position of gear wheel 21 shown in Fig. 1, atorsion-proof connection between crank wheel 18 and gear wheel 21 ISestablished via a tooth system 25 between gear wheel 21 and bearing tube181 of crank wheel 18: the torsion-proof connection can be released bysliding gear wheel 21 in FIG. 1 upward. A coupling is therefore locatedin the drive chain, one coupling part of which is formed by crank wheel18 with bearing tube 181; the other coupling part, which can be actuatedby separating lever 24, is formed by gear wheel 21. The coupling is heldclosed by coupling spring 23. Gear wheel 21 meshes with its outer teeth22 with a drive pinion 28 formed on a driven shaft 26 of electric motor27. It should be noted that, in FIG. 1, crank driving mechanism 16 isshown in a position in which piston 15 assumes its anterior dead-centerposition, shown at the left in FIG. 1. To ensure clarity in the drawing,piston 15 is shown further to the left than it would be under actualcircumstances, however.

Hammer tube 13, which is rotatably supported in housing 10, is startedrotating by electric motor 27 via a gear unit 30, so that the tool,which is axially displaceable with limitation in the tool holder and ismounted in a non-rotative manner, also rotates. Gear unit 30 includes aring gear located on hammer tube 13, the ring gear being retained onhammer tube 13 in an axially displaceable and rotatable manner, a bevelgear 32 meshing with teeth on ring gear 31, and a gear wheel 33 withexternal teeth 34 that is connected with bevel gear 32 in torsion-prooffashion. Bevel gear 32 and gear wheel 33 are rotatably retained inhousing 10, and external teeth 34 mesh with drive pinion 28 on drivenshaft 26 of electric motor 27.

The drilling hammer described in this manner can be used in threeoperating modes. In the “impact drilling” operating mode, electric motor27, which has been turned on, brings hammer tube 13 into rotation andactivates air cushion striking tool 14; for this purpose, the couplingin the drive chain of air cushion striking tool 14 (as shown in FIG. 1)is closed and ring gear 31 is connected with hammer tube 13 in atorsion-proof manner. In the “chiseling” operating mode, only the aircushion striking tool 14 is activated; for this purpose, the coupling inthe drive chain of air cushion striking tool 14 is closed and ring gear31 is decoupled from hammer tube 13. In the “drilling” operating mode,air cushion striking tool 14 is idled and hammer tube 13 is startedrotating; for this purpose, the coupling in the drive chain of aircushion striking tool 14 is opened and ring gear 31 is connected withhammer tube 13 in a torsion-proof manner.

An operating mode change-over switch 35 serves to set these threedifferent operating modes of the drilling hammer, the operating modechange-over switch including a single, manually operated control button36 and a switching mechanism 37 having a stable and compact design.Control button 36 is located in housing cover 12 such that it isprotected and user-friendly. It includes a control button lower part 38and a control button cap 39 that overlaps a collar 121 formed on housingcover 12. Control button lower part 38 is inserted in a multi-step boreencompassed by collar 21 and secured to the underside of control buttoncap 39. Control button lower part 38 includes an eccentric pin 40 thatextends at a right angle from the underside of control button lower part38, and a switching ramp 41 that is located on the underside of controlbutton lower part 38, extends in the circumferential direction ofcontrol button lower part 38, thereby rising in the direction of therotational axis of control button 36, i.e., downward in FIG. 1.

Switching mechanism 37 also includes separating slide 24 mentionedabove; the separating slide is guided in housing 10 in a verticallydisplaceable manner and bears with a U-bent slide end 241 on theunderside of control button lower part 38 or switching ramp 41, and,with its other U-bent slide end 242, it overlaps gear wheel 21 thatforms the displaceable coupling part of the coupling in the drive chainof air cushion striking tool 14. Upper slide end 241 is pressed by aspring 41 shown only schematically in FIG. 1 against the underside ofcontrol button lower part 38 and/or against switching ramp 41, wherebythe spring force of spring 42 is greater than the spring force ofcoupling spring 23, so that, in the range of rotation of control buttonlower part 38 in which upper slide end 241 leaves switching ramp 41,gear wheel 21 is slid upwardly by spring 42 and lower lever end242—while tensioning coupling spring 23 in FIG. 1—so far that toothedconnection 25 between crank wheel 18 and gear wheel 21 is released, thecoupling in the drive chain of air cushion striking tool 14 is thereforeopened and striking tool 14 is turned off. As illustrated in the profileof switching ramp 41 in FIG. 9, the switching ramp extends across anapproximately 270° circumferential angle of control button lower part38, so that separating slide 24 is released to be displaced by spring 42only in a range of rotation of approximately 90° of control button 36.

Switching mechanism 37 also includes a switching element 43 slid ontohammer tube 13, which is shown in a perspective drawing in FIGS. 2 and3, and a shift fork 44 that connects switching element 43 to controlbutton 36. Switching element 43 is composed of a coupling ring 45 madeof plastic, from which two diametrally located cantilevers 46 integralwith coupling ring 45 extend axially. Each cantilever 46 is providedwith a recess 47 on its free end opposite the ring and are pretensionedoutwardly in the radial direction of coupling ring 45. When the twocantilevers 46 are pressed together, an actuator ring 48 can be insertedinto recesses 47, the actuator ring being composed preferably of metal.On its inside facing hammer tube 13, actuator ring 48 includes twodiametrally located, radially projecting guide splines 49 that arepositioned in corresponding guide grooves 50 recessed in the outside ofhammer tube 13. Two further guide grooves 50 are recessed in hammer tube13. each of which accommodates one of the two cantilevers 46. Thedimensions of cantilevers 46 and guide splines 49 are preferably thesame, so that all four guide grooves 50 can be configured identically.On its outside facing away from hammer tube 13, actuator ring 48includes a plurality of equidistantly spaced, radially projectinglocking splines 51 that are configured such that they can be insertedaxially in corresponding axial recesses 52 on the underside of ring gear31 facing hammer tube 13. A locking part 53 in the housing isdiametrically opposed to the insertion openings of axial recesses 52 inring gear 31, the locking teeth of which are configured such thatlocking splines 51 can be inserted axially into locking part 53 and canbe positioned in a form-locked manner in the direction of rotation.Locking part 53 is located with axial clearance from axial recesses 52in ring gear 31 such that, once actuator ring 48 slides out of ring gear31, actuator ring 48 can still assume a position in which its lockingsplines 51 do not yet engage in locking part 53. In this “neutral” or“zero” position of actuator ring 48, hammer tube 13 is not coupled toring gear 31 or locking part 53 in the housing, enabling hammer tube 13to rotate freely. Coupling ring 45 includes a recess or an annulargroove 54 into which a radially directed projection 55 of shift fork 44engages.

Flat shift fork 44, which is shown in a sectional view in FIG. 1 and atop view in FIGS. 5 through 8 and is preferably made of plastic, extendswith its free end on which the projection is located over hammer tube 13to annular groove 54 in coupling ring 45; it turns downward at the endof hammer tube 13 and extends underneath control button lower part 38.The coupling of shift fork 44 to control button 36 takes place via asynchronizing spring 56 and eccentric pin 40 on control button lowerpart 38. Synchronizing spring 56 is configured as a coil spring withlong legs 561, 562 U-bent at a right angle to the spring axis, thespring being slid onto a bolt 57 projecting upward at a right angle fromshift fork 44 and bearing with its two long legs 561 and 562 ondiametral points of eccentric pin 40 in a non-positive manner, thepoints nearly aligning with each other in the sliding direction of shiftfork 44 (FIGS. 5 through 8). Eccentric pin 40 is located on controlbutton lower part 38 at an angle α relative to the longitudinal axis ofshift fork 44 such that, when control button 36 rotates by 90°, fourrotated positions of eccentric pin 40 result, each being offset from theother by a distance a/2 as viewed in the sliding direction of shift fork44, as shown in FIG. 5. The overall displacement travel of shift fork 44is a, after which shift fork 44 bears against a stop 59 in the housing.The upper slide end 241 of separating slide 24 is shown in theillustrations in FIGS. 5 through 8, the slide end extending past theunderside of control button lower part 38 and bearing on switching ramp41 across a circumferential angle of nearly 270°.

Control button cap 39 is shown in a top view in FIG. 4. It includes agripping segment 58 on which a marking tip 581 is configured. Markingtip 581 indicates the setting position of control button 36, that is,the “chiseling” mode (M), the “impact drilling” mode (S), and the“drilling” mode (B), which are set by operating mode change-over switch35. In addition, a “neutral” or “zero” position (0) is provided, inwhich only the air cushion striking tool 14 is active but not the rotarydrive for hammer tube 13, and hammer tube 13 can rotate freely and atrandom in housing 10.

The mode of operation of operating mode change-over switch 35 is asfollows:

If control button 36 is set, as shown in FIG. 4, such that marking tip581 points to position M, shift fork 44 is displaced furthest to theleft in FIG. 1 along the maximum displacement travel a, as shown in FIG.5. Accordingly, switching element 43 is displaced by shift fork 44 asfar to the left as possible; as a result, actuator ring 48 with itslocking splines 51 is pressed into locking part 53 in the housing.Hammer tube 13 is fixed in housing 10 in a torsion-proof manner by thetorsion-proof connection of actuator ring 48 with hammer tube 13 viaguide splines 49, cantilevers 46 and guide grooves 50, and there is noconnection between hammer tube 13 and ring gear 31. When electric motor27 is turned on, freely rotating ring gear 31 and air cushion strikingtool 14 are driven by gear unit 30, since separating slide 24 bears withits upper slide end 241 on switching ramp 41 and, as shown in FIG. 1, isdisplaced downward so that coupling spring 23 holds the coupling betweencrank wheel 18 and gear wheel 21 closed. Since only air cushion strikertrain 14 is activated, the tool is driven only by air cushion strikertrain 14 with an axial striking motion.

If control button 36 is turned out of position M into position 0 by 90°in FIG. 4 in the counter-clockwise direction, shift fork 44 is displacedby eccentric pin 40 and synchronizing spring 56—as shown in FIG. 6—tothe right along displacement travel a/2 in FIG. 1. Switching member 43in FIG. 1 is displaced to the right along the same displacement path bycoupling ring 45; as a result, locking splines 51 on actuator ring 46disengage from locking part 53, and actuator ring 48—as shown in FIG.1—assumes a central position between locking part 53 and ring gear 31.Hammer tube 13 is released to rotate freely, but is not started rotatingby electric motor 27. Air cushion striking tool 14 remains activated,since separating slide 24 is also held in this rotational position ofcontrol button 36 by switching ramp 41 in the position shown in FIG. 1.

If control button 36 is turned to control button position SB, shift fork44 is displaced to the right along displacement path a/2 in FIG. 1 and,after eccentric pin 40 covers half of the rotation path, it contactsstop 59 in the housing. Eccentric pin 40, which moves further, deflectsspring leg 561 of synchronizing spring 56 (FIG. 7). Shift fork 44, whichis being displaced by the distance a/2, pushes actuator ring 48 in FIG.1 so far to the right that locking splines 51 slide into axial recesses52 in ring gear 31 in a form-locked manner and therefore connect hammertube 13 to ring gear 31 in a torsion-proof manner. Electric motor 27 nowbrings hammer tube 13 and, therefore, the tool holder and the toolretained in the tool holder in a torsion-proof manner into rotation. Aircushion striking tool 14 remains activated, since upper slide end 241 ofseparating slide 24 has not yet left switching ramp 41 (refer toposition SB in FIG. 9).

If control button 36 is now turned further by 90° into setting positionB, eccentric pin 40 returns along rotation distance a/2. Since eccentricpin 40 in setting position SB had previously moved rotation distance a(FIG. 7) given a displacement travel of shift fork 44 by a/2 whiledeflecting spring leg 561, this return of eccentric pin 40 does notcause shift fork 44 to become displaced. Actuator ring 48 thereforeretains its engaged position in ring gear 31. As a result of therotation of control button lower part 38 around this further 90°,switching ramp 41 has slid out of the region of the upper lever end 241of separating slide 24, so that separating slide 24 is pushed upward byspring 42 in FIG. 1 until it bears against the switching ramp-freeregion of control button lower part 38 and, thereby, its lower lever end242 pushes gear wheel 21 upward while pressing coupling spring 23together, so that the external teeth between gear wheel 21 and bearingtube 181 of crank wheel 18 become disengaged and the coupling in thedrive chain of air cushion striking tool 14 is opened. Air cushionstriking tool 14 is therefore decoupled from electric motor 27 and,finally, hammer tube 13 is started rotating by electric motor 27. Puredrilling work can now be carried out with the tool retained in the toolholder in a torsion-proof manner.

It is possible, of course, to turn control button 36 out of its settingposition M in the opposite direction of rotation directly into settingposition B and then, from here, further to setting position SB and then0. Nothing about the mode of operation of switching mechanism 37 changesas a result.

1. A drilling hammer comprising a hammer tube (13) that is rotatablysupported in a housing (10), the hammer tube being rotationallydriveable by a driven wheel (31) of a gear unit (30) sitting on thehammer tube (13), with a striking tool (14) located in the hammer tube(13), the striking tool including a piston (15) that can be driven witha reciprocating motion, and an operating mode change-over switch (35)for the “impact drilling” and “chiseling” operating modes, the operatingmode change-over switch including a manually actuatable control button(36) and a switching mechanism (37) connected with the control button(36), the switching mechanism coupling the hammer tube (13) to thedriven wheel (31) when in the “impact drilling” operating mode of thecontrol button (36) and fixing the hammer tube in a non-rotative mannerin the housing (10) when in the “chiseling” operating mode, wherein theswitching mechanism (37) includes an actuator ring (45) fixed on thehammer tube (13) in an axially displaceable and torsion-proof manner,the actuator ring including at least one radially projecting lockingspline (51) on its outer side facing away from the hammer tube (13), thelocking spline being designed to slide in an axial direction directionin a form-locked manner into at least one axial recess (52) in thedriven wheel (31) and into locking toothing (53) in the housing, andwherein, to fix the actuator ring (48) in a torsion-proof and axiallydisplaceable manner on the hammer tube (13), the actuator ring (48)includes at least one radially projecting guide spline (49) on an innerside facing the hammer tube (13), and the hammer tube (13) includes atleast one axial guide groove (50) on an outer side facing the actuatorring (48), in which the guide spline (49) is situated in thecircumferential direction in a form-locked manner.
 2. The drillinghammer as recited in claim 1, wherein the actuator ring (48) is locatedon the side of the driven wheel (31) facing away from the control button(36) and is connected—underneath and past the driven wheel (31)—with acoupling ring (45) slid onto the hammer tube (13) on the other side ofthe driven wheel (31), the coupling ring being coupled to the controlbutton (36) such that actuating the control button brings about an axialdisplacement of the actuator ring (48).
 3. The drilling hammer asrecited in claim 2, wherein the connection between the actuator ring(48) and coupling ring (45) is created using at least two cantilevers(46) projecting axially outwardly from the coupling ring (45).
 4. Thedrilling hammer as recited in claim 3, wherein the cantilevers (46) areaxially displaceable and are accommodated in the circumferentialdirection of the hammer tube (13) in axial grooves (50) in the hammertube (13) in a form-locked manner.
 5. The drilling hammer as recited inclaim 2, wherein the cantilevers (46) are integrally molded on thecoupling ring (45) and the actuator ring (48) is accommodated inrecesses (47) that are formed close to the end of the cantilevers (46)furthest away from the coupling ring in the outer side of thecantilevers (46) facing away from the hammer tube (13).
 6. The drillinghammer as recited in claim 2, wherein an annular groove (54) is formedin the outside of the coupling ring (45), in which a radially directedprojection (55) of a shift fork (44) coupled with the control button(36) is displaceably guided.
 7. The drilling hammer as recited in claim6, wherein the control button (36) is fixed in the housing (10) suchthat it is pivotable around a rotation axis, and the shift fork (44) iscoupled via a synchronizing spring (56) to an eccentric pin (40)extending out of the control button (36) and positioned with radialclearance from the axis of rotation.
 8. The drilling hammer as recitedin claim 7, wherein the synchronizing spring (56) is a coil spring withlong legs (561, 562) bent at a right angle to the spring axis, and thesynchronizing spring (56) is mounted on a bolt (57) formed on the shiftfork (44) and bears, in a non-positive manner, with both of its legs(561, 562) on diametral points of the eccentric pin (40) opposite eachother in the sliding direction of the shift fork (44).
 9. The drillinghammer as recited in claim 1, wherein a setting position is assigned tothe control button (36), in which the displacement position of theactuator ring (48) of the switching mechanism (37) is set such that theactuator ring (48) is neither in torsion-proof engagement with thedriven wheel (31) nor in torsion-proof engagement with the housing (10).10. The drilling hammer as recited in claim 1, wherein the controlbutton (36) has a selling position for the “drilling” operating mode inwhich the striking tool (14) is decoupled, and the striking tool (14) isdecoupled by a sliding motion of a switching mechanism part (37) that istriggered by the control button (36) and travels at a right angle to thehammer tube (13).
 11. The drilling hammer as recited in claim 10,wherein a coupling with two coupling parts held in engagement with eachother by a coupling spring (23) is located in the drive chain for thestriking tool (14); one of the coupling parts is configured such that itcan be displaced against the force of the coupling spring (23) by theswitching mechanism part actuated by the control button (36).
 12. Thedrilling hammer as recited in claim 11, wherein a switching ramp (41) isfom,ed on the control button (36), which rises in the rotationaldirection of the control button (36) at a right angle to the undersideof the control button (36), and the switching mechanism part is aseparating slide (24) guided in an axially sliding manner, that bearsagainst the switching ramp (41) in a non-positive manner and against thedisplaceable coupling part.
 13. The drilling hammer as recited in claim12, wherein the non-positive connection between the separating slide(24) and the coupling part, and between the separating slide (24) andthe switching ramp (41) is established by a spring (42) acting on theseparating slide (24), the spring force of which is greater than thecoupling spring force of said coupling spring (23), directed againstsaid spring force of said spring (42).
 14. The drilling hammer asrecited in claim 11, wherein the drive chain for the striking tool (14)includes a crank wheel (18) of a crank driving mechanism (16) engagingin the piston (15) of the striking tool (14), and a gearwheel (21) thatmeshes with a drive pinion (28) driven by an electric motor (27), thecrank wheel (18) and the gearwheel (21) form the coupling parts that areengaged with each other via axial toothing (25), and the coupling spring(23) is configured as a compression spring that bears axially betweenthe crank wheel (18) and the gearwheel (21).